1. Field of Invention
The present invention relates to an earphone device, and more particularly to an earphone device having different bass performances by adjusting a volume of a back chamber of a speaker.
2. Related Art
FIG. 1 shows an earphone device according to the prior art. As shown in FIG. 1, the earphone device includes a case 10 having an accommodating portion 11. The accommodating portion 11 includes an inner chamber for accommodating components such as a speaker and a drive circuit. A bass tube 12 extends from the accommodating portion 11 of the case 10. When the speaker is disposed in the accommodating portion 11, the inner chamber is in communication with a space in the extended bass tube 12, so as to form a back chamber of the speaker.
In the initial stage for designing the case 10 of the earphone device according to the prior art, a volume of the bass tube 12 is determined according to specific consumer groups. However, the low-frequency characteristics of the earphone device are primarily determined by the volume of the bass tube 12. Here, the low frequency refers to frequencies in a range from 20 Hz to 200 Hz, which is further divided into low bass, mid bass, and upper bass. The frequency range of the low bass is 20 HZ to 40 Hz, the frequency range of the mid bass is 40 Hz to 100 Hz, and the frequency range of the upper bass is 100 Hz to 200 Hz. Therefore, consumers who often listen to classical music pay special attention to the low bass performance, while consumers who often listen to dance music with strong beats care more about the upper bass performance.
Currently, various music players have a very large storage capacity, and can store hundreds of or even thousands of songs. For a consumer who does not have specific favorite music styles, many different styles of songs may be stored in the music player, and the songs require different bass performances. Therefore, if an earphone device similar to that in the prior art is used for converting and outputting the sounds, the tone quality performance is more or less unsatisfactory for users.